Production of dialkyl sulphates



- lo pounds.

Patented Jan. 21,` 1930 UNITED ASTATES PATENT OFFICE TO SETH B. HUNT, TRUSTEE, OF MOUNT KISCO, NEW YORK PRODUCTION OF DIALKYL SULPHATES Application ledMarch 16, 1923. Serial No. 625,486.

This invention relates to the production of 'dialkyl sulphates. More particularly, the invention relates to the extraction of ethylene, propylene, oil gas to produce dialkyl sulphates and other valuable products therefrom.

The dialkyl sulphates are neutral organic compounds of great value as a starting point for the preparation of many organic com- Alcohols, ketones and esters may be prepared from dialkyl sulphates with ease, and a preparation of dialkyl sulphates leads p therefore t-o the production of many other organic compounds. The esters which may-be derived from the higher dialkyl sulphates,

such as isopropyl amyl sulphate, are compounds having properties analogous to the ordinary banana oilof commerce, and may therefore terial for the ordinary uses to which it is put. In the commercial cracking of, petroleum oil to obtain gasoline and other. oil fractions therefrom there is always a large amount of oil gas or still gas which is formed in the process which contains a very considerable proportion of unsaturated hydrocarbons. The gasoline and other fractions produced in the process also contain some unsaturated hydrocarbons which must be removed therefrom because vof the unstable character of these compounds. lIf unsaturated hydrocarbons are not removed from the various oi fractionstheytends to unite with each other Cor to polymerize on standing and form hydrocarbons of higher molecular weight.

The primary object of the present invention is to provide a process of separating unsaturated hydrocarbons from petroleum products by which the unsaturated hydrocarbons may be recovered, and by which polymerization and resinification of the unsaturated hydrocarbons may be substantially prevented.

Another object of the invention is to provide av process of separating unsaturated'hy'- amylene, and other olefines from be used as a substitute for this mabutylene, amylene,

drocarbons in such a manner that they may be readily available for converting into other organic compounds.

A further object of the invention is to provide a process of removing amylene and higher oleines from oil gas whereby they may be substantially completely removed therefrom by sulphating withoutl the use of sulphuric acid (ILSOQ which acid has a strong tendency to polymerize the higher oleflnes.

With these and other objects in view the invention consistsin a new `composition of matter and a process of separating unsaturat- .ed hydrocarbons from oil gas whereby a new composition of matter is obtained, as is hereinafter described and particularly defined in the claims.

The present invention is based upon the discovery that the higher olefines such as hexylene and heptylene may be substantially completely absorbed in a -lower alkyl sulphuric acid, such as ethyl and isopropyl sulphuric acid, with the prof duction of neutral dialkyl sulphates.

Heretofore it has been customary to use sulphuric acid (H2SO4) for carrying on the absorption of olefines from oil gas and the absorption was controlled so as to obtain acid suplhate without utilizing all of the sulphuric acid employed asthe absorption agent. In the present invention, however, a normal sull phate is obtained together with some acid sulphate and therefore a veryy much larger amountof olefines in proportion to the quantity of sulphuric acid employed may be absorbed according to the present process. Ful'- y thermore, the use of alkyl sulphuric acid in absorbing olefines permits the use of higher temperatures in absorption without excessive polymerization taking place, and the rate of reaction is not so rapid as to form tars which usually result from a process of this kind. In other words, of maximum value, the reactions herein described are carried on under sulphating conin order 4to obtain products A(isopropyl ditions, by which is meant conditions whereby the reaction is substantially directed to the production of snlphated products and reactions productive of tarry, resinous and charred products in substantial proportions are avoided, so far as practicable.

The reactions upon which the process depends may be illustrated by the reactions which take place with ethylene, propylene,

and higl'ier oletines such as amylene.

Ethylene which is present in the oil` gas treated is absorbed in concentrated sulphuric acid of substantially 66 B. strength at a temperature ofA approximately 80'to 90O C. with the formation of 'ethyl sulphuric acid according tol the following equation:

1. oiii=oin+inso.=Ciecmnsoi' (Ethylene) (Sulphuric (Ethyl sulphuacid) ric acid) Propylene reacts with the sulphuric -acid in the cold or at temperatures below 30o C. with a formation of isopropyl sulpliuric acid, the reaction taking place according to the following equation:

2. CH3`CH=CH2+H2S04=(Cll'cilzCH-SOJI (Propylene) (Sulphuric (Isopi'opyl-su1- This reaction between sulphuric acid and propylene takes place according to the rule that the HSC, group unites with the carbon atom of the,oleline compound which is combined with the lowest number of hydrogen atoms.

The reaction between isopropyl sulpliuric acid and ainylene to form the dialkyl sulphate, isopropyl amyl sulphate, takes place according to the following equation:

(cHnCH-son cnw= (ciiigcirosog-'o-cl-,ii11

(Amylene) (Isopropyl amyl sulphate) sulphuric acid) lnthe reaction of oleines other than amylene with isopropyl sulphuric' acid products similar to the above dialkyl sulphate are formed having the general formula:

which is a flow sheet` or a 'diagrammatic representation of the steps ofthe process whereby the invention is carried out.

Oil gas which preferably comes from the pressure stillsof the ordinary refineries is iirst'cooled in any desired manner and is then treated with an absorbing menstruum comprising mainly a mixture of-isopropyl sulphuric acid and ethyl sulphuric acid, the absorbing menstruum having been derived from a later step in the process, as will be explained.

It is desirable that the reacting materials be in contact n nder pressure for a considerable period of time at a low temperature, preferably at or below 30 C. In order to accomplish the absorption under these conditions the oil gas is passed upwardly through y i struuin consisting of The invention may be best explained in lconnection with the accompanying drawing a tower o f the ordinary commercial type, the

tower'being cooled in any desired manner. y

The absorbing inenstrnum comprising isopropyl sulphnric acidand ethyl sulphuric acid is passed downwardly through the tower 1, asis indicated inthe flow sheet, in a direction countercuire'nt to that of the gas. The tower 1 has ar series of cooling coils therein 'for regulating the temperature of the liquid and gas passing therethrough, and has also a series of' trays over which the liquid flows in order to come into intimate contact with the gas particles contalning the olefines.

the prolonged contact of the gas and absorb- 4 ing menstruuin the alkyl sull'ihlirie acids correspondin g d ialk' the equation ing withdrawn at the bottom ofthe tower 1. The gas, from which the higher oleiines have been removed, passes out of the top of the tower and. is lead preferably to the bottom of a second tower, 2, similar to tower l, in which .an absorbing mcnstruum comprising mainly yl sulphate illustrated by -3 above, the reaction product beployed the temperature is maintained below 3 0" C. in order to minimize'the polymerization of the olenes in the gas. If concentrated sulph'uric acid is employed the temy perature is maintained preferably below 20o C. lf dilute sulphuric acid or a sulphuric acid having a gravityof from 1.65 to 1.8 is used however, higher temperatures may be employed in the absorption without-danger of excessive polymerization of the olefines in the gas taking place. An absorbing mengas oil or a comparatively-high boiling petroleum distillate may be employed with sulphui'ic acid in place of the absorbing menstruuin above mentioned, whichgwill permit` the use of higher temperatnres during the absorption while minimizing the amount of polymerization taking place. lf desired, the propylene may be recovercd'in an acid menstrninn consisting of concentrated sulphuric acid and ethyl sulphuric acid substantially asdescribed Vin the 'copending application of Born and lsham,

Serial N o. 294,013, filed May 1, 1919,

When using an absorbing menstruum consisting of ethyl sulphuric acid and sulphuric @acid it is desirable to maintain the amount 'in the rst absorbing tower for removing oley 80 therein react with the olefi'nes to produce the 2. 1n order to absorb the ethylene inl the which is formed in the first reaction chamber or tower lis a yellow liquid which is insoluble in water lbut is soluble in ether. The material may be hydrolyzed: by boiling with water by which alcohols are produced and sulphuric acid is liberated. The alcohols which are thus formed may be used for the production of other chemical products in any reaction where alcohols may be employed as a starting material. The .reaction of hydrolysis of dialkyl sulphates may be illustrated in the case of isopropyl amyl sulphate, for example, as taking place according to the following equation:

( Sulamyl sulphate) oil gas concentrated sulphuric acid of substantially 60 B. is passed through the tower in a .direction countercurrent to that of the gas passing therethrough. The besttemperature for the absorption of ethylene is approximately 90 C., which is ordinarily attained through the heat evolved in the reaction. During cold weather, however, the

heat of reaction will not be sufficient to raise the temperature to the required degree. Heating coils similar to thc cooling coils of towers 1 and 2 may be employed in the tower 3' and may be used whenever necessary, in order to obtain the desired degree of heat during the absorption of the ethylene in the sulphuric acid. The oil gas from which now substantially all of the unsaturated hydrocarbons have been removed is withdrawn from the top of the tower and may be passed to storage or may be burned directly in suitable gas burners.

By the process outlined above a new product isobtained consisting'of a normal alkyl sulphate containing two ethyl groups or an ethyl group, or an isopropyl group, and anl alkyl group higher than the ethyl group such as a propyl, butyl, amyl, hexyl, or heptyl group. An alkyl sulphate derived from isopropyl sulphuric acid is also obtained, containing an alkyl group such as the butyl,

amyl, hexyl or heptyl group, forming therebyl the corresponding isopropyl alkyl sulphate. Said new product is a mixture of dialkyl sulphates composed of molecules containing either an ethyl or an isopropyl group in each molecule and both the ethyl and isopropyl groups being present in the mixture. Said product is useful in forming esters of formic,

`acetic and like acids, it being easy to so conduct the esterification that esters of the heavier alcohols are formed together with van alkali alkyl sulphate. Said product, moreover, may be used to produce mixed ethers by careful distillation With a limited regulated amount of water. Other uses for said product will occur, no doubt, to those skilled in the chemical arts. 'The crude product (SODI'ODYI Wa r) (Islopropyl (A cohol) alcohol) phuric acid) If it is desired to obtain single or unmixedy 2 alcohols, the alcohols lmay be separated by distillation and rectification according to the usual procedure. The secondary alcohols which are formed in the reaction may be oxidized if desired to the corresponding ketones by the ordinary chemical methods of oxidation.

Under certain conditions of operation it may be advisable to modify the process by recovering ethylene in oil gas in a manner different from that above described. The process may also be modified by not recovering the-.ethylene at all, but allowing it to pass with the gas, after the absorption of propylene and higher defines-therefrom, to storage, or to burners, where it will be burned together with the gas. 1n the modification in which ethylene is not recovered the process will be carried on in the following manner: ,Cil gas from the pressure stills is cooled and treated with isopropyl sulphuric acid to remove the higher olefines from the oil gas in the tower 1. The amount of isopropyl sulphuricacid employed in the absorption tower can v4be regulated so as to produce substantially nothing but isopropyl alkyl sulphate with the higher olefines in the gas. The reaction product is .withdrawn at'the bottom of'tower 1 while the gas from which the higher ole'fines have been removed passes out at the top of the tower and is led to the bottom of the tower 2 through which it passes in a countercurrent direction to the propylene t ,medium. The amount of acid may be regulated so asto obtain substantially isopropyl sulphuric acid with no appreciable amount of free sulphuric acid. By regulating the amount of sulphuric acid employed so as to avoid the presence of free sulphuric acid i skilled in the art. to limit the invention to the procedurevas described except as deined in the claims. 1

there will be a small amount of di-isopropyl sulphate present which however will not interfere in the subsequent reaction with the higher olelines and will act merely as a neutral inactive material. 'The isopropyl sulphuric acid orreaction product formed in the tower 2 is withdrawnthrough a pipe at the bottom of the tower and is preferably passed to storage from which the amounts required for the reaction in the tower l may be withdrawn and supplied thereto at the desired rate. The oil gas from which the higher olefines and propylene have been abstracted is withdrawn from the top of the tower 2 and to burners. This process as outlined will be employed when the price of ethyl alcohol is so low or when the cost of abstracting ethylene is so high that it would not pay to recover the ethylene. y

Various modifications may be made in the processes as described to produce dialkyl sulphates and-other .valuable reaction products Without departing from the spirit or scope of the invention, as will be apparent to one .It is desired therefore not Having thus described the invention, what is claimed as new is:

l. A process of extracting unsaturated hydrocarbons from oil gas which comprises passing oil gas through an absorbing soluf' tion comprising a mixture of alkyl sulphuric oletines from acids to absorb the higher olefines therefrom, `said solution being essentially free of active constituents other than alkyl sulfuric acids, thereafter passing the gas through an absorbing solution comprising ethyl sulphuric acid to absorb propylene therefrom, and viinally passing the gas'into contact with concentrated sulphuric'acid to absorb ethylene from the gas, all said steps being carried out under sulphating conditions.

2. A process of extracting unsaturated hydrocarbons from oil gas which comprises passing oil gas through an absorbing solution comprising ethyl sulphuric. acid and isopropyl sulphuric acid to absorb higher the said oil gas, said solution being essentiallyfree of active constituents other than alkyl sulfuric acids, thereafter p assin'gthe gas through an absorbing solu-v tion comprising ethyl sulphuricacid to absorb propylene therefrom and to obtain the solution to be employed for the absorption of higher olefines, finally passing the gas into contact with concentrated sulphuric acid to absorb ethylene. from the gas, all said steps beingcarried out under sulphating conditions. .3. A process of strippinggas which comprises passing gas containing ethylene but from which propylene and 'higher oleines have been removed, into contact with sulphuric-acid of approximately 66 Bestrength passes from thence to storage or 'at a temperature of approximately 90 C. to absorb ethylene from the gas, forming a solution comprising ethyl sulphuric acid, cooling the solution obtained thereby, thereafter passing gas containing ethylene and propylene but from which higher olefines have been removed, into contact with the cooled solution to absorb propylene therefrom, and thereby forming a solution comprising a mixture of ethyl sulphurie acid and isopropyl sulphuri'c acid, said second solution being essentially free of active. constituents other than alkyl sulfuric acids, finally passing' gas containing ethylene, propylene, and higher olefines into contact with the solution of mixed alkyl sulphuric acids to obtain dia'lkyl sulphates, and separating the solution so obtained, all said steps being carried out under .sulphating conditions.

4. A process of extracting unsaturated hydrocarbons from oil gas comprising passing the gas under sulphating conditions through an absorbing menstruum essentially free of act-ive constituents other than alkyl. sulphuric acid and then passingv the remaining gas through sulphuric acid lunder sulfating conditions. p 4

5. A process of extracting unsaturated hydrocarbons from oil gas comprising passing the gas under sulphating conditions through two different alkyl sulphuric'acid absorbing menstruums and then passing the remaining gas through a sulphuric acid menstruum under sulfating conditions.

0. A process of extracting olefines in the olefine series higher` than ethylenes from oil gas comprising passing the gas under sulphating conditions through an absorbing menstruum consisting essentially of alkyl sulphuric acid, said absorbing menstruum comprising ethyl sulphuric acid and being essentially free of active constituents other than alkyl sulfuric acids. p

p 7. A process of extracting unsaturated hydrocarbons from oil gas, comprising passing. the gas under 'sulphating conditions through an absorbing menstruum consisting essentially of alkyl sulphuric. acid, said absorbing menstruum comprising ethyl and isopropyl sulphuric acids and being' essentially free of active constituents other than alkyl sulfuric acids. i,

8. -A process of separating butylene, amylene, hexylene and heptylene from oil gas comprising treating the gas under sulphating conditions and under pressure with an acid menstruum comprising isopropyl sulphuric acid at a temperature below 30o C. .f

9. A Iprocess of extracting olefineshigher in the olefine series than propylene from oi] gas comprising 'treating the-gas under sull phating conditions andunder pressure with an acid menstruum comprising ethyland isopropyl sulphuric acids at a temperature b elow 30 C. r 1

- 10. A process of separating oleines from oil gas which comprises treating the oil gas with an acid mentsruum including isopropyl Vsulphuric acid to abstract higher olefines therefrom, thereafter treating the oil gas with fluid containing sulphuric acid as an active constituent to abstract propylene therefrom and to obtain an acidmenstruum of isopropyl sulphuric acid and employing the menstruum so obtained for the first absorption to remove the higher olefines from the gas, all said steps being carried out under sulphating conditions.

11. A process of separating olefines from oil gas comprising cooling the gas, passing the gasl under pressure into intimate contact with an acid reacting menstruum containing mineral acid radicals but less reactive than sulfuric acid of equal concentration at a temperature below 30 C. to absorb higherunsaturated olefines therefrom, and passing the gas into intimate contact with liquid containine sulphuric acid at a temperature below 30 to remove propylene therefrom, all said steps being carried out under esterfying conditions.

12. A process of producing dialkyl sulphatesfrom oil gas which comprises coolin the gas containingamylene and other higher oleiines to a temperature below 30 C. under/- pressure and thereafter passing the gas into contact with isopropyl sulphuric acid under sulphating conditions.

13. As a. composltion A of matter, a mixture of dialkyl sulfates composed of molecules containing an alkyl group having more than one and not more than three carbon atoms in eachmolecule and both ethyl `and isopropyl groups being present in the mixture.

14. A process of separating propylene, amylene, hexylene and heptylene from oil gas comprising treating the gas under sulfating conditlons wlth 'an acid menstruum comprisg isopropyl sulfuric acid at a temperature vbelow 30 C.

' 15. A process of extracting olefines higher in the olene series than propylene from oil gas, comprising treating the gas under sulfating conditions with an acid menstruum comprising ethyl and isopropyll sulfuric acids at a temperaturebelow 30 C.

16. The process of forming dialkyl sulfates comprising passing a sulfuric acid menstruum countercurrent to and incontactwith an olefine-containing gas under sulfating conditions until the liquid menstruum is essential- 1y free of active constituents other thanalkyl sulfuric acid, and lpassing saicl'alkyl sulfuricA acid menstruum in contact with and c'ountercurrent to olene containing gas under sulfating-conditions to form dialkyl sulfates yfrom said define-containing gas.

ROBERT M. IsrmM.-

In testimony whereof I aix `my signature CERTIFGATEy 0F CORRECTION.

Patent No. 1', 744, 227. Granted limmary 2i, 1930, `to

` ROBERT M. ISHAM.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: inge 3, iine 20, for "60" read "66"; and that the said Letters` Patent shouid be read with this correction Ytherein that the same may conform to the record oi the case in the Patent Office. K v

Signed and sealedtbis 13th day of May, A. D. 1930,.

M. J. Moore. (Seal) Acting Coissioner ci Patents.

CERTIFICATE 0F CGRRECTIN.

Patent Nm i9744,227. Granted January 21, 1930, t0

ROBERT M. ISHAM.

Tt is hereby certified that error appears in the printed specification o the above numbered patent requiring correction as follows: Page 3, line 20, for "60" reati "66"; and that the said Letters Patent shouid be read with this eorrection therein that the same may conform to the record of the case in the Patent Cities,

Signed and sealed this 13th day of May, A. D, W3C,

M. J. Moore, (Saai) Acting Commissioner o Patents. 

